Preconcentration of Cd(II) and Pb(II) ions using dye modified silica gel

In this study, silica gel was physically modified with Coomassie Brilliant Blue G-250 (Acid blue 90) dye (Si-CBB) to obtain a new solid sorbent, and used to develop an analytical method for seperation and preconcentration of Cd(II) and Pb(II) ions which were found at trace levels in natural water samples. In the developed method, analyte ions were determined by flame atomic absorption spectrometry (FAAS). Structural characterization of new modified silica gel sorbent was examined using FT-IR spectrometry and SEM monitoring tecniques. The parameters including, pH, sorbent amount, sample flow rate, sample volume, eluent concentration, flow rate and volume which are effective on the solid phase extraction efficiency were optimized using experimental optimization procedures. The optimized parameters for simultaneous sorption and elution of the target analytes were pH=5, sample flow rate=3,9 mL/min, sorbent mass=0,5 g, sample volume=39,1 mL, eluent flow rate=3,1 mL/min, eluent HCl concentration=0,6 mol/L and eluent volume=5,7 mL. The validation of the proposed method was validated by the analysis of ICP multi-element standard as a reference standard and recovery values of 96,83% and 96,00% were obtained for Cd(II) and Pb(II) ions, respectively. In the developed preconcentration method, the maximum adsorption capacity values for Cd(II) and Pb(II) ions were determined as 59,0(±3,4) µg/g and 133,4(±9,7) µg/g, respectively. Also, in this method the limit of detection (LOD) and limit of quantification (LOQ) were as 10,28 µg/L and 34,26 µg/L for Cd(II), 39,91 µg/L and 133,04 µg/L for Pb(II), respectively. Preconcentration factor was achieved as 8 for Cd(II) and 11 for Pb(II). Additionally, the proposed method was succesfully applied to analyte spiked and unspiked natural water samples.